Welcome to AMP

 

F. Sassi conducted a set of simulations that describe the WACCM response to changes in the gravity wave parameterization during FY06. These simulations show that the gravity wave processes can have first order effects on the climate of the middle atmosphere, influencing the occurrence of stratospheric warmings, the magnitude of some model biases (cold pole problem), and ultimately affecting the stratosphere-troposphere coupling mechanisms. It is also shown that the inclusion of processes-consistent sources of gravity waves in the troposphere helps for example the simulation of the tropical oscillations. Other major collaborative activities included studies of the effect of solar variability in the middle atmosphere including historical simulations of the past 50 years (in collaboration with R. Garcia and D. Marsh in the Atmospheric Chemistry Division); investigations of dynamical variability in the middle atmosphere (in collaboration with L. Polvani and A. Charlton at Columbia University); continued work comparing WACCM simulation data and lidar observations to better evaluate the gravity wave parameterization in the mesosphere-lower thermosphere region (in collaboration with C-Y She at Colorado State University), and completion of a model inter-comparison that investigates the effects of climate change on the Brewer-Dobson circulation (in collaboration with N. Butchart at the Met Office – UK). Also during FY06, the greenhouse component of the WACCM model was completely redesigned to allow integration of the model without interactive chemistry and with specified heating rates above 60 km. Not only this component is about twice as fast the older version, but it is possible now to run WACCM with boundary fields generated by the fully interactive model to extend studies of the effect of interactive chemistry to the mesosphere and lower thermosphere region.